Operating mechanism of single-chain grabs.



G. H. F. BURGDORP.

OPERATING MECHANISM OF SINGLE CHAIN GRABS.

APPLICATION FILED 11017.15, 1912. 7

Patented Apr. 8, 1913.

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CHRISTIAN HEINRICH FRIEDRICH BURGDORF, OF ALTONA, GERMANY.

OPERATING MECHANISM OF STNGLE-CHAIN GRABS.

Specification of Letters Patent.

Patented Apr. 8, 1913.

Application filed November 15, 1912. Serial No. 731,498.

To all whom it may concern:

Be it known that I, CHRIs'rIAN HEINRICH FRIEDRICH BURGDORF, a subject of the German Emperor, and resident of Grosse-Gartnerstrasse 59/63, Altona, Germany, have invented certain new and useful Improvements in the Operating Mechanism of Single-Chain Grabs, of which the following is a specification.

This invention relates to single chain grabs with automatic closing and releasing mechanism, and it consists principally in the simplified device for locking and releasing the grab jaws. For this purpose a number of sleeves or shells working one within another are employed and during the drawing up of the chain the locking head, consisting of these sleeve members, is raised into a bell or hood wherein it is held by catch members engaging under the outer-' most sleeve of the locking head; when this has occurred the grab is opened by the slackening of the chain, while the outer sleeve of the locking head is held up in the hood member. The innermost sleeve of the locking head drops when the chain is slackened, and in this way catch levers mounted on an intermediate sleeve are released; when the chain is drawn up again these catch members engage with it causing the intermediate sleeve to be raised, and a flange on the said sleeve is thus caused to release the catch members of the hood. In this way the looking head is liberated from the hood and can be lowered again by the chain, with the grab opened out. When the grab falls upon the material to be raised, the intermediate sleeve of the locking head falls and the catch levers thereon are moved automatically into a position in which they leave the chain free to rise through the sleeves of the head. This simplified construct-ion makes it possible to reduce appreciably the weight of the grab mechanism, and consequently the efficiency in raising the material by the grab is increased. The locking and releasing head is connected with the grab through a Cardan suspension device, so that whatever may be. the angle at which the grab settles upon the mud or other material to be raised, the looking or releasing head is always brought into an approximately vertical position when the chain begins to be drawn upward, the consequence of which is that the device operates with certainty in closing the grab,

whatever may be the position taken up by the grab.

Referring now to the accompanying drawings:Figure 1 is a side elevation of the grab and the locking and releasing head in the closed position. Fig. 2 is a similar view showing the grab opened, and the hood which fits over the locking head partly in section. Figs. 3, 4, and 5 are views, each half in section and half in elevation, showing the locking and releasing head in three different positions.

The grab consists of the two jaws or scoops b and c which are pivotally supported on the shaft a. The shaft a passes through a cross-piece cl, which is revoluble upon the shaft and accommodates the chain wheel 6, which is also revolubly mounted on the shaft (4. The lower ends of the four links or rods 8 are connected by means of pins f to the outer edges of the jaws b and 0, while the upper ends of the said rods fit over two oppositely arranged pins g on a ring 2; (see Fig. 8). This ring 2 is connected to a sleeve h, the said sleeve in with two other sleeves 1, and working over it, constituting the principal parts of the locking and releasing head. The sleeve in is formed in two parts in order to permit of fitting of the other sleeves over it, and at the upper end the sleeve h is formed with a flange Z.

The lower part of the said sleeve which is rigidly connected to the upper part by being screwed thereon or otherwise firmly at tached thereto, carries the oppositely placed pins m by which the ring 2 is supported, and also has a pair of projections n. The intermediate sleeve 6 is formed with afiange 0 at its upper end, and a substantial flange an at its lower end; beneath the flange w are projecting lugs 29 carrying a pair of elbow levers o, w pivoted on pins 1" in the said lugs. The arms w of these elbow levers are provided with counterweight project-ions q,

while the arms a; work through longitudi-;

nal slots marked 6 in the lower half of the sleeve member 72. The outermost sleeve 70 of the locking and releasing head is formed with a projection at the bottom with a cone shaped upper face 3 and with an inwardly directed flange a while the upper end of the said sleeve has an inwardly directed flange u.

The pins g of the ring 2 which support the rods 8, are arranged at right angles to the pins m by which the ring 2 is suspended;

when it comes to rest in the material to be lifted, without the locking and releasing head being placed in an ineffective position, or appreciably deflected from the vertical line.

The end of the chain K is suitably attached to the ring 2, the chain being carried around the chain wheel 6 which is revolubly mounted on the shaft on and in the cross-piece d, the chain passing outward through the sleeve in and through a hood or arranged to fit over the locking and releasing head. This hood may be hung from or attached to the crane jib or the like as will be well understood. The hood carries a pair of catch members {5 which are pressed inward by means of springs, counterweights or the like.

The device works in the following way hen the grab is being raised with the jaws b and 0 closed and full of material, the three sleeves h, 2' and It? of the locking and releasing head occupy the position shown in Fig. 1 and in detail in Fig. 3. Then the locking head is raised into the hood as the cone-shaped surface 3 of the sleeve 70 first presses back the catch members t, which engage under the projection of the sleeve 70 after a slight further raising of the chain. In this way the locking and releasing head is held fast in the hood on (Fig. Up to this point the sleeve it has been in the raised position resting by its flange Z against the inner flange u of the sleeve is. The projections n of the raised sleeve 72. hold the arms to of the elbow levers "a, 'w, in the raised position, so that the arms a stand vertical as shown, that is to say, they are out of reach of the chain K. By lowering the chain the jaws b and 0 can now be opened, whereupon first the sleeve it falls and its flange Z comes to rest on the flange 0 of the intermediate sleeve 2', as shown in Fig. 4. The elbow levers o, w

are thus liberated and the arms 10 fall on account of their weights 9, so that the arms o are made to project into the path of the chain K. The chain can now be paid out fartherthrough the locking and releasing head, but it. cannot be drawn back again without being engaged by the arms 4;. The chain is paid out until the two grab jaws reach a position such as that shown in Fig. 2, and the contents of the grab will have been discharged. After this, the chain K is drawn up. The arms a engage with the first member of the chain coming opposite to them so that the sleeves h and i are raised with the grab jaws b, 0 in the open position. The flange m of the sleeve 2', as the latter rises, presses against the inclined faces of the catch members (5 of the hood a, pressing back and rel-easing the, said catch members before the flange w comes to lie close against the bottom face of the sleeve (Figs. 2 and 5). Now the locking head can be lowered with the grab in the open position. When the grab jaws come to rest on the material to be raised, the chain becomes slackened and the sleeve 2' drops so that the arms 10 of the elbow levers strike againstthe projections a of the sleeve member h, while he latter member is held up owing to the resting of the grab on the ground. The arms 1) are consequently moved back so that the chain is released as in Fig. 3, and it may now be drawn up again, causing the jaws b and 0 of the grab to close and lift the material which they have scooped up. The sequence of operations is then repeated as above set forth.

The invention is not limited to the precise details of construction shown. Any of the parts may be replaced by their known mechanical equivalents. Either of the sleeves 2' or 70 may be made in two parts in order to enable them to be fitted together. More than two catch members may be used on the hood, or any other convenient catch arrangement of a similar type may be adopted.

What I claim is:

1. The combination with a grab and chain, of an automatic locking and releasing mechanism therefor comprising three sleeve members through which the chain passes and which are adapted to work one over another, means connecting one of said sleeve members to the jaws of the grab and to the end of the grab chain respectively, catch mechanism on the second of said sleeves adapted when liberated to engage the chain but to be held out of action when the second sleeve falls relatively to the first, and means adapted to engage and hold up the third sleeve member, and to be disengaged therefrom by upward movement of the second sleeve relatively to the third sleeve.

2. The combination with a grab and chain, of an automatic locking and releasing mechanism therefor comprising three sleeve members through which the chain passes and which are adapted to work one over another, a ring, means pivotally supporting said ring on one of said sleeve members and links pivotally connected to said ring and to the jaws of the grab, together constituting a universal joint connection between the grab and said sleeve member, catch mechanism on the second of said sleeves adapted when liberated to engage the chain but to beheld out of action when the second sleeve falls relatively to the first, and means adapted to engage and hold up the third sleeve member, and to be disengaged therefrom by upward movement of the second sleeve relatively to the third sleeve.

3. The combination with a grab and chain, of an automatic opening and closing connecting it to the jaws of the grab in such mechanism therefor comprising a threemanner as to form a universal joint connecpart locking and releasing head through tion between the grab and head. which the chain passes, catch mechanism in In testimony whereof I have signed my 15 said head for engaging the chain and adaptname to this specification in the presence of ed to be released by relativef movement of the two subscribing witnesses.

arts of said head means or en 'a in and golfing up Said adapted g s a w CHRISTIAN HEINRICH FRIEDRICH BURGDORF. leased by relative movement of the parts lVitnesses: of said head, and a member with pivots con- FRIEDRICH JULIUS Po'rHs, nect-ing it to one part of the head and links ERNEST H. L. MUMMENHOFF.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of ratents.

Washington, D. G. 

